Add Spacing to Recycler View Linear Layout Manager Using Item Decoration

In this article we will learn about, item decoration in Android and how we can use it to add even spacing between the child items.

A RecyclerView without spacing will look like the image below but in most cases, we want to add spacing between the items. [You can see there are no margins between the views and only elevation]

recycler-view-without-decorator

A more traditional option is adding margins in the list item xml file. If we take this route, we will soon end up with uneven spacing issues with vertical margins. [There are even left, right, top, bottom margins for all the rows except the last item in the first image and in the subsequent image, the top margin for the first item is half of the other items]

recycler-view-without-decorator

recycler-view-without-decorator

The best way is to add the ItemDecoration to the RecyclerView as it affects the individual items and you can have more control over them.

Kotlin:

/**
 * Add vertical, horizontal spacing to the recycler view
 */
class DefaultItemDecorator(private val horizontalSpacing: Int,
                           private val verticalSpacing: Int) :
        RecyclerView.ItemDecoration() {

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        super.getItemOffsets(outRect, view, parent, state)
        outRect.right = horizontalSpacing
        outRect.left = horizontalSpacing
        if (parent.getChildLayoutPosition(view) == 0) {
            outRect.top = verticalSpacing
        }
        outRect.bottom = verticalSpacing
    }
}

The above class extends ItemDecoration and overrides getItemOffsets where the left, right, bottom margins are set based on the constructor injected margins. Along with these margins top margin is added only for the first element for uniformity.

recyclerview.addItemDecoration(DefaultItemDecorator(
resources.getDimensionPixelSize(R.dimen.provider_name_horizontal_margin),
resources.getDimensionPixelSize(R.dimen.provider_name_vertical_margin)))

Add the ItemDecoration to the RecyclerView as above. This adds equal spacing to the RecyclerView items as shown in the figure below.

recycler-view-with-decorator

Instead of adding all the margins using the ItemDecoration, we can add the left, top, right margins in the item layout file and add a bottom margin to the last item using the below ItemDecoration.

Java:

/**
 * Recycler view item decorator sets spacing for the bottom of the last item
 */
public class LinearSpacesItemDecoration extends RecyclerView.ItemDecoration {

    private int spacing;

    public LinearSpacesItemDecoration(int spacing) {
        this.spacing = spacing;
    }

    @Override
    public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent,
                               @NonNull RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        if (parent.getAdapter() != null && parent.getChildLayoutPosition(view) ==
                parent.getAdapter().getItemCount() - 1) {
            // Add bottom margin only for the last item
            outRect.bottom = spacing;
        }
    }
}

Popular posts from this blog

How to Read Metadata from AndriodManifest File

Metadata tags are key-value pairs and one of the decent ways to access the API keys from the libraries. They are added to the AndroidManifest.xml under the application tag and are available through the PackageManager . If you have worked with third-party libraries or even with App shortcuts, Downloadable Fonts, Firebase MLKit, you may have come across metadata tags. In the article, let’s add the metadata tags to the app module’s Manifest file and read the metadata key-values and the key-resource from a library module both in kotlin and java. Add meta-data: Add metadata to the app module's AndroidManifest.xml file under the application tag. You can add as many metadata elements as you want and you can also add metadata under the activity, service, broadcast receiver, content provider tags. <meta-data android:name= "com.gsrikar.library.LIBRARY_ACCESS_KEY" android:value= "masndfiu4er9funwikesd" /> <meta-data and
Read more

Mr Phone - Find The Next Best Phone You Want To Buy

Image
Want to buy a phone and not sure which phone to choose? Mr Phone is a phone search application and is here to help you find the best phone. The application was built by acidandrage and is available in the Google Play Store with In-app purchases. Search for your device and detailed specs gets loaded along with the image. You can tap the image for more pics or save the phone specs to view later. You can compare specs of any two phones or choose to use the Best Fit option. The Best Fit option of the app will show you the list of best-matched phones based on the preferred specs you've selected. Sections like New Releases and Popular shows the newly released phones and the phones that became most popular recently. While Stories section gives you to the Top Stories about smartphones, apps, and the Events section notifies you about the launch events of the smartphones. Great Day Readers! To give us more insights into the application development, Ashish Hooda, Head of
Read more

Add Options Menu to Activity and Fragment

Image
Options Menu contains a set of primary menu items that are accessible to the user. In this article, we will take a look at how to implement the options menu in an Android Activity or a Fragment. Right click on the res directory in Android Studio and select Android Resource File option. It opens the Resource File creation modal where we need to enter the file name and select Resource Type as Menu. Clicking on OK button creates main_menu.xml under menu directory. Now add the following items to the XML file. <menu xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> <item android:id="@+id/search" android:icon="@drawable/ic_search_white" android:orderInCategory="100" android:title="@string/action_title_search" app:actionViewClass="androidx.appcompat.widget.SearchView" app:showAsAction="ifRoo
Read more

Create Assets Folder, Add Files and Read Data From It

Image
Sometimes, we need to read the data stored in the files during runtime and want to make sure the data is not tampered by the Android build system. In this article, we will take a look at how to create the assets folder using Android Studio and read the stored data from it. First, Right-click on the module name or the package name. This opens an option window where we need to select the Assets Folder option by hovering over New and then on the Folder option. Now, we will see a window where we change the folder location and the source set. Change the values if necessary otherwise keep the defaults and click Finish. It may trigger a Gradle Sync. Irrespective of the sync, the Assets folder is created and is visible in the module. Now, Right-click on the Assets folder and click on the File option by hovering over the New option. Enter the name of the file name and click Enter to create the file. The file with the name user_details.json is created under the assets folder. Add some JSON
Read more